This invention relates generally to optical beam deflection systems and, more particularly, to optical beam deflection systems suitable for use in optical radar, target designation, communications or optical display apparatus. Optical radar is a term used to describe apparatus for detecting the position of "target" objects using electromagnetic radiation at optical frequencies, including ultraviolet and infrared frequencies. Target designation involves the illumination of selected targets so that they can be identified and tracked by other independent systems. Optical beams used in radar and similar apparatus are typically transmitted as high-energy coherent beams, which must be deflected by some means in a rapid manner if multiple targets are to be addressed in a short period of time. There is a similar requirement for rapidly selecting received optical beams in a receiver system.
A special problem arises if the apparatus must process information relating to a large angular field. This is typically the situation that exists in a radar application, in which there are a number of "targets," each of a relatively small angular size, sparsely populating a large angular field. Practically the same situation exists in some communications applications, in which communications "targets," such as satellites, are scattered across a wide angular field of view. Similarly, in some optical display systems it may be desirable to display multiple independently movable images on a display screen, using one or more optical beams that are rapidly scanned across a wide angular field of view.
In each case, the optical beam deflection system must deflect an optical beam through relatively large angles, and there is a requirement for both a high speed of deflection and a high degree of precision in positioning the beam. A purely mechanical beam deflection system can cover a large angular field with high resolution, but the speed or agility of the beam is limited by mechanical inertia. Electro-optical, acousto-optical, and low-inertia mechanical beam deflection systems, and scanning lasers, are all capable of high speeds of deflection, but have a limited number of resolvable angular positions.
Accordingly, there is a need for a beam deflection system capable of rapid operation over a wide angular field, and with a high degree of precision. The present invention satisfies this need.